For the last decade or more, Europe’s governments have been trying to resist covert influence operations from adversaries like Russia and China.

Now they have a very different challenge: Fending off overt efforts by Elon Musk and Donald Trump’s MAGA movement to seize territory, oust elected leaders and empower far-right causes and parties.

Even before he retakes office, Mr. Trump is making threats — perhaps serious, perhaps not — to acquire the territory of NATO allies like Canada and Denmark. And Mr. Musk, the president-elect’s biggest financial supporter, is using his social media platform X to bring the far-right Alternative for Germany party into the mainstream and smear the leaders of Britain’s center-left Labour Party.

It is not clear if Europe’s political immune system has the antibodies to defend against these new incursions.

This is not the first time a Trump ally has attempted to build a bridge with the European far right. In 2018 and 2019, the Trump adviser Stephen K. Bannon held meetings with far-right politicians across Europe. But the political landscape now is very different. The governments of Germany and France have collapsed; far-right parties are on the rise in those countries, and are already in power in several others across the continent.

A senior official from the first Trump administration, who is in line for an even more senior role in the second, was blunt in his assessment: Europe, he said, has no idea what is coming its way.

‘A very rich person expressing his opinions’

Mr. Musk spent a $250 million slice of his $400 billion fortune to help Donald Trump get re-elected. He arguably had just as much influence on U.S. politics through his own notoriety and ownership of X, the social media network formerly known as Twitter.

He aggressively campaigned against Kamala Harris (in one case sharing a fake video of her describing herself as a “diversity hire” who does not “know the first thing about running the country”) and interviewed Trump live on the platform. He is now deploying a similar playbook in Europe.

In Britain, Mr. Musk revived a decade-old “grooming gangs” scandal that unfolded while Prime Minister Keir Starmer, whose center-left Labour Party is in power, was head of public prosecutions.

Fanning the flames that were kindled by right-wing media outlets, Mr. Musk has called Mr. Starmer “utterly despicable” and says he should be “in prison.” Last week he asked his 212 million followers to vote on whether “America should liberate the people of Britain from their tyrannical government.”

According to British media reports, Mr. Musk is also considering a $100 million donation to Britain’s far-right Reform Party, which would be the country’s largest political donation ever. The party’s leader, Nigel Farage, one of the chief campaigners for Brexit, has met Trump several times, most recently at Mar-a-Lago last month.

“MAGA hates Starmer,” the former Trump administration official told The Times. He spoke on the condition of anonymity to offer his candid views while he is being considered for a role in the second Trump administration.

“MAGA loves Meloni,” he added, referring to Italy’s right-wing prime minister, Giorgia Meloni, “as long as she meets her deportation targets.”

Mr. Musk’s SpaceX is also in talks with Ms. Meloni’s government to provide secure military communications through its Starlink satellite network. At a news conference last week, she described Mr. Musk as a “very rich person who is expressing his opinions.”

‘Musk is normalizing us’

In Germany, which is holding snap federal elections next month, Mr. Musk is encouraging voters to vote for the far-right AfD, offering it the legitimacy that has long been denied to a party under surveillance by Germany’s domestic intelligence service for its links to neo-Nazis.

In an opinion piece for a major German newspaper published Dec. 28, he called the AfD the last “spark of hope” for Germany. The country, he said, is “teetering on the brink of economic and cultural collapse.”

On Thursday he live-streamed a 75-minute conversation with Alice Weidel, the AfD’s candidate for chancellor, on X, giving her the same platform he gave Trump five months earlier.

Since Mr. Musk first endorsed the AfD in December, Ms. Weidel’s posts on X have routinely gone viral, in part because he reposts them, along with numerous neo-Nazi accounts that have been reinstated and amplified. Researchers watching the online scene say far-right German influencers now post on X in English to get Mr. Musk’s attention.

Germans won’t vote for the AfD just because an American billionaire asks them to. But social media is a tool that can shift public opinion, taking ideas that were once considered extreme and inserting them into the mainstream over time.

What has kept the AfD out of power despite becoming the second most popular party in the country is a national taboo against working with the far right. The memory of Hitler, who formed a coalition with centrist conservatives, has so far kept this firewall in place.

“The firewall between the AfD and the White House is officially gone and that makes the German firewall look silly,” the AfD’s co-leader, Tino Chrupalla, told me. “Musk is normalizing us.”

Overt vs. Covert

U.S. influence campaigns in other countries are not new. During the Cold War America lent its support to friendly nations and parties and intervened — sometimes aggressively — in countries seen to be ideological adversaries.

But now the MAGA movement seems to be intentionally sowing discord within U.S. allies. That’s disorienting for Europeans who grew up imbibing American lessons about democracy after World War II.

“I can’t remember a comparable case of interference in the election campaign of a friendly country in the history of the western democracies,” said Friedrich Merz, the leader and chancellor candidate of the center-right Christian Democrats. His party is leading in the polls but will need a coalition partner to form a government.

The United States remains the main guarantor of European security as the war in Ukraine has shown. It is also Europe’s biggest export market, making the prospect of tariffs a powerful threat for European economies. And Europe has no technology companies on par with those coming out of Silicon Valley, including Mr. Musk’s X platform and his Space X satellite company.

Europe’s dependency on Russian energy long hampered its response to the Kremlin’s meddling. But the dependency is much greater in the case of the United States.

Add to that the fact that the American interference is not covert, it is happening in broad daylight, which makes fighting back that much harder.

Exploiting existing grievances

Influence campaigns work best when they tap into existing grievances. As in the United States, Europe’s trust in institutions fell in the aftermath of the 2008 financial crisis and the pandemic. Voters have become more hostile toward immigration and more worried about the cost of living and the economy. There is a growing sense that centrist leaders on left and right have failed them on these issues.

Millions of people in Europe are angry with the establishment, said Matthew Goodwin, a conservative author and commentator. “It’s not being orchestrated by Trump or Musk.”

“Musk has not created the AfD,” Mr. Goodwin added. “It helps the AfD that he is getting them attention but the underlying driver of this are policy choices that were made over the past decade.”

Mr. Musk’s provocations in Europe may be designed for maximum chaos rather than electoral success. In Britain, he trashed Nigel Farage, leader of the far-right Reform Party, after Mr. Farage declined to endorse Mr. Musk’s demand that a far-right agitator be released from prison.

“Both the Kremlin and the forces around the libertarian-authoritarian camp around Musk want to sow chaos in Europe and get rid of the liberal democratic elites,” Thorsten Benner, director of the Global Public Policy Institute in Berlin, told the German outlet Die Zeit. “We have to arm ourselves against that. But the biggest danger for our democracies comes not from the outside but the inside. Those fighting election campaigns should focus on the problems that concern voters.”

Similar levels of infighting and chaos also exist within the broader MAGA movement. Back in United States, there are signs that those in Mr. Trump’s hard line anti-immigration inner circle are tiring of Mr. Musk, especially after a spat about whether the country should expand work visas for highly skilled immigrants. In an interview with the Italian newspaper Corriere della Sera on Sunday, Mr. Bannon called Mr. Musk “truly evil” and vowed to “take this guy down.”

Whatever the direct impact of American interference on Europe’s political map in coming years, Trump is determined to enforce his priorities in Europe whoever is in government.

“At the end of the day, Trump is going to be so much more aggressive with Europe in terms of advocating uncompromisingly for the U.S. position that it doesn’t actually matter who’s in charge,” the former Trump official said. “They key thing is America First. Everything else is a distraction. Trump is going to use American strength to get his way.”

Most American parents hardly give thought to polio beyond the instant their child is immunized against the disease. But there was a time in this country when polio paralyzed 20,000 people in a year, killing many of them.

Vaccines turned the tide against the virus. Over the past decade, there has been only one case in the United States, related to international travel.

That could change very quickly if polio vaccination rates dropped or the vaccine were to become less accessible.

Robert F. Kennedy Jr., a longtime vaccine skeptic who may become the secretary of health and human services, has said the idea that vaccination has nearly eradicated polio is “a mythology.”

And while Mr. Kennedy has said he’s not planning to take vaccines away from Americans, he has long contended that they are not as safe and effective as claimed.

As recently as 2023, he said batches of an early version of the polio vaccine, contaminated with a virus, caused cancers “that killed many, many, many, many, many more people than polio ever did.” The contamination was real, but research never bore out a link to cancer.

Aaron Siri, a lawyer and adviser to Mr. Kennedy, has represented a client seeking to challenge the approval or distribution of some polio vaccines on the grounds that they might be unsafe.

Those efforts appear unlikely to succeed. And there is widespread support for vaccination among prominent Republicans, including President-elect Donald J. Trump and Senator Mitch McConnell, who had polio as a child.

But the secretary of health and human services has the authority to discourage vaccination in less direct ways. He or she could withdraw federal funds for childhood vaccination programs, hasten the end of school mandates in states already disinclined toward vaccines or fuel doubts about the shots, exacerbating a decline in immunization rates.

If polio vaccination rates were to fall, scientists say, the virus could slip into pockets of the country where significant numbers of people are unvaccinated, wreaking havoc once more. The virus may be nearly eradicated in its original form, but resurgence remains a constant threat.

Any decision the Trump administration makes regarding the polio vaccine is likely to ripple across the globe, said Dr. David Heymann, an infectious disease physician at the London School of Hygiene and Tropical Medicine and former leader of polio eradication at the World Health Organization.

“If the U.S. takes away the license, then many other countries will do the same thing,” he said. To have polio resurge when it is so close to eradication “would be very, very, very, very sad.”

Before 1955, when the vaccine was introduced, polio disabled more than 15,000 Americans each year and hundreds of thousands more worldwide. In 1952 alone, it killed 3,000 Americans after paralysis left them unable to breathe.

Many of those who survived still live with the consequences.

“People really underestimate how horrific polio was,” said Dr. Karen Kowalske, a physician and polio specialist at University of Texas Southwestern Medical Center in Dallas.

Many who recovered now suffer “post-polio syndrome”: Some of the original symptoms, including muscle weakness and respiratory problems, return.

Dr. Kowalske tends to about 100 post-polio patients who need braces, wheelchairs or other devices to cope with progressive weakness. Some are older adults who became infected before the vaccine was available; others are middle-aged immigrants from countries where polio remained a problem for much longer than in the United States.

To some survivors, the idea of polio’s return is unfathomable.

Carol Paulk contracted the disease in 1943, when she was just 3. Her right leg never recovered, and for the rest of her life she has walked with a pronounced limp and has been in near-constant pain.

Ms. Paulk is among the luckier ones. Until recently, she did not suffer the breathing, swallowing or digestive problems that often torment polio survivors.

She has had “a wonderful, wonderful life” with a husband and three daughters, a law degree and extensive travel abroad.

But always, everywhere, she is calculating how far away the next seat is, how long her energy will hold out and whether a given activity is worth debilitating pain the next day.

She didn’t participate in the 1963 March on Washington or play sports, as she desperately wanted to, or go hiking, skiing and bicycling with her husband.

If there were a public hearing about the polio vaccine now, “I would go, and I would take off my brace, and I would let them see my leg and ask them, is that what they want for their children?” she said.

Polio disables many fewer children now. Vaccination has scrubbed the virus from most of the planet, slashing the number of cases by more than 99.9 percent and preventing an estimated 20 million cases of paralysis.

Still, the virus has turned out to be a stubborn enemy, and eradication has been set back over and over again.

In 2024, 20 countries reported polio cases, and the virus was detected in wastewater in five European countries, decades after its official elimination from the region, and in Australia.

“Any reduction in coverage rates increases the risk of polio anywhere,” said Oliver Rosenbauer, a spokesman for the World Health Organization’s polio eradication program.

There are three types of polioviruses, and eradication requires that all three disappear. For years, the goal has been tantalizingly close.

Type 2 was declared vanquished in 2015, and Type 3 in 2019. Type 1 now circulates only in Afghanistan and Pakistan. In 2021, the two countries together had just five cases; in 2024, they had 93.

But those figures tell only part of the story. In a surprising twist, an oral vaccine used in some parts of the world has kept poliovirus circulating long after it should have died out.

In most low- and middle-income countries, health officials still rely on an oral vaccine given as two drops on the tongue. It is inexpensive and easy to administer, and it prevents transmission of the virus.

But it contains weakened virus, which vaccinated children can shed into the environment through their feces. When there are enough unvaccinated children to infect, the pathogen slowly spreads, regaining its virulence and eventually causing paralysis.

The problem is this: Since 2016, the oral vaccine used for routine immunization has not protected against Type 2 virus. Global health authorities made a deliberate decision to reformulate the vaccine on the grounds that naturally occurring Type 2 virus had disappeared.

That turned out to be premature. More Type 2 virus had been shed by orally vaccinated children in some parts of the world than officials had anticipated. When some nonimmunized children, or those given the newer oral vaccine, encountered this “vaccine-derived” Type 2 virus, they became infected and paralyzed.

Vaccine-derived poliovirus now paralyzes more children than naturally occurring virus does. For example, Nigeria eliminated all so-called wild-type polio in 2020. But in 2024, the country saw 93 cases of Type 2 vaccine-derived virus, more than one-third the global total.

None of this is a problem for Americans — as long as they are vaccinated.

The inactivated polio vaccine (I.P.V.) used for routine immunization of American children protects against all three types of polio. These formulations contain dead virus, and so cannot cause disease or revert to a dangerous form.

But like some other vaccines for infectious diseases, they do not fully prevent infection or transmission of the virus. This aspect is among the criticisms of Mr. Siri, Mr. Kennedy’s adviser.

Still, it is less important than the vaccines’ near-perfect power to prevent paralysis, experts said.

“Yeah, yeah, it’s true, I.P.V. doesn’t prevent transmission,” said Dr. William Petri, an infectious diseases physician and past president of the W.H.O.’s polio research committee. “But, boy, that’s the best thing since sliced bread at preventing paralysis.”

It does mean, however, that people vaccinated with I.P.V. can keep the virus circulating, even when they themselves are protected against illness and paralysis.

So here’s a realistic scenario that worries researchers: Someone who was vaccinated with the oral polio vaccine in another country might bring the virus into the United States and then shed it, in its weakened form. This has already happened in other countries.

So long as most of the population remains vaccinated, this is not likely to set off an epidemic. But if the virus makes its way into communities with low vaccination rates, it may spread, and then revert to a virulent form that can cause paralysis.

That is what happened in New York in 2022, when polio struck a 20-year-old unvaccinated member of an ultra-Orthodox Jewish community in Rockland County.

The vaccination rate in that county was just over 60 percent, compared with the national average of 93 percent.

The virus that paralyzed the young man had been circulating for months, and it was later detected in the sewage of multiple New York counties with vaccination rates hovering around 60 percent, prompting the state to declare an emergency.

Genetically related polioviruses were detected in wastewater samples in Britain, Israel and Canada, suggesting widespread transmission. The authorities later found two distinct vaccine-derived Type 2 polioviruses in New York wastewater, suggesting two separate importations.

If polio were to re-emerge in the United States, it is unlikely to be as horrific as it was in the pre-vaccine decades. Many older adults still remember that as children they were not permitted to swim in rivers or pools, or anywhere the virus might lurk.

“The reason we weren’t allowed to play in rivers in the ’50s is because raw sewage was dumped into the rivers,” Dr. Heymann said.

That is no longer the case, so there “wouldn’t be massive transmission immediately in the U.S.,” he added.

But even if just a few children were to become paralyzed, “it would be awful.”

High-level cease-fire talks appeared to be gaining momentum on Monday as Arab and American mediators pressed for an agreement to halt the fighting in Gaza and release hostages held by Hamas before President-elect Donald J. Trump assumes office on Jan. 20.

It was still unclear whether the parties had reached resolution on central disputes that have proved insurmountable in previous rounds of negotiations, but officials briefed on the talks have expressed cautious optimism in recent days about the possibility of concluding a deal.

For months, repeated rounds of talks have seen hopes rise only to be dashed days later, with both Israel and Hamas blaming the other for the impasse.

If a deal is achieved, it would bring some respite to Palestinians in Gaza, who have endured miserable conditions in displacement camps and relentless bombardments by Israel, and the families of hostages taken from Israel, who have suffered for months wondering about the fate of their loved ones.

Who are the players?

• The lead mediators in the talks are Qatar and Egypt, shuttling messages between Israel and Hamas. The Qatari prime minister, Sheikh Mohammed bin Abdulrahman bin Jassim Al-Thani, and the director of Egypt’s General Intelligence Service, Maj. Gen. Hassan Rashad, have been the top officials representing their countries in the negotiations.

• David Barnea, the chief of Israel’s foreign intelligence service, Mossad, is one of Israel’s main negotiators, alongside Ronen Bar, the head of the Shin Bet, a domestic security service, and Maj. Gen. Nitzan Alon of the Israeli military. Ophir Falk, a foreign policy adviser to Prime Minister Benjamin Netanyahu, has also participated in important meetings related to the negotiations.

• Khalil al-Hayya, a senior Hamas official based in Doha, is the militant group’s chief negotiator and has interfaced with Qatari and Egyptian officials about the details of a possible agreement.

• The United States has used its leverage to encourage Israel and Hamas to sign on to a deal. Bill Burns, the C.I.A. director, and Brett McGurk, a senior White House official, have crisscrossed the Middle East, pressing for a breakthrough in the talks. Steve Witkoff, Mr. Trump’s Middle East envoy, has also made trips to Qatar and Israel, meeting with top officials there.

What are they negotiating?

Israeli officials hope to secure the release of at least some of the roughly 100 hostages who have been held in Gaza since the Hamas-led attack on southern Israel on Oct. 7, 2023, that ignited the ensuing war in the territory.

Hamas leaders want to achieve an end to the war in Gaza, which has severely weakened the group’s armed wing and government, led to the displacement of nearly two million people, and reduced cities to rubble. Hamas officials have also said they are seeking a complete Israeli withdrawal from Gaza, the return of displaced people in the south of the enclave to the north, and the entry of materials for reconstruction.

What are the biggest obstacles?

• A major obstacle to the success of the talks has been the permanency of a cease-fire. While Hamas has demanded a comprehensive end to the war, Mr. Netanyahu has said he wants a “partial” deal that will allow Israel to resume the war after freeing hostages.

• Israel has been demanding vague language in the text of an agreement that leaves room for a resumption of fighting at some point, according to a Palestinian familiar with the matter and two Israeli officials. Mr. Netanyahu has feared that his right-wing coalition partners could take down his government and jeopardize his political future if he agrees to a deal that ends the war in Gaza, analysts say.

• Hamas has not suggested it would be willing to compromise on its demand to end the war. Last week, Osama Hamdan, a senior Hamas official, told a gathering in Algeria that there must be “an absolute end to the aggression.”

One young soldier from North Korea said he didn’t know where he was fighting when he was sent from his isolated homeland to the frontline of the war between Russia and Ukraine. When asked whether his parents knew where he was, another North Korean soldier shook his head.

The three-minute video clip that President Volodymyr Zelensky of Ukraine posted on the social media ​platform X on Sunday showed a Ukrainian official questioning two North Korean prisoners of war with the help of a Korean interpreter. ​The Ukrainian authorities announced their capture​ on Saturday, saying they were the first North Korean troops to be taken alive. Mr. Zelensky later offered to exchange them for Ukrainian prisoners of war held in Russia.

The soldiers’ answers came in footage provided and edited by Ukraine, which controlled the production and release of the video. It offered a tiny, but rare, glimpse into the mind-set and preparedness of ​an estimated 11,000 North Korean troops deployed to help Russia’s war against Ukraine.

They appeared to back up what South Korean and U.S. officials have said in recent weeks: North Korean troops were taking heavy casualties in a foreign war waged in an unfamiliar territory while their government was keeping their deployment a secret to its people.

South Korea’s National Intelligence Service told lawmakers in Seoul on Monday that it estimates 300 North Korean soldiers have been killed and 2,700 others wounded in battles​ against Ukraine. The White House has put the toll even higher.

​Memos found with dead North Korean soldiers indicated that their government had urged the highly indoctrinated troops to end their own lives rather than be captured​ in the battlefield, according to South Korean lawmakers who briefed journalists after a closed-door meeting with the spy agency, echoing an assertion made by Mr. Zelensky. One North Korean soldier was trying to blow himself up with a grenade, shouting the name of ​North Korea’s leader, Kim Jong-un, when ​he was shot by Ukrainian troops, they said.

North Korea has not responded to reports of its troops captured or killed by Ukraine forces. ​It has never publicized the ​deployment ​or large shipments of ​North Korean artillery shells and other weapons​ sent to Russia to help its war against Ukraine​, although ​they marked the country’s first intervention in a major armed conflict overseas in decades.

In the video released by Mr. Zelensky, the voice of an official questioning the North Koreans was distorted, perhaps to prevent their identification, and the captured troops were clearly still wounded. Ukraine said the soldiers had received medical care and had been taken to Ukraine’s capital, Kyiv, for interrogation. But by posting the video clip online, Ukraine also appeared to use the POWs in its messaging to the West.

The Ukrainian leader has seized the involvement of North Korean troops for Russia as a way to try and galvanize more support from allies. South Korea, too, has cited North Korea’s growing military alliance with Russia as a source for international concern.

Experts say that comments from prisoners of war should be assessed in light of the power imbalance between captors and captives, with the knowledge that the prisoners may not be speaking freely and could be motivated by their own safety concerns or a desire for good treatment.

According to the rules governing treatment of prisoners of war under the Geneva Conventions, governments are supposed to protect a prisoner of war from being made into a “public curiosity,” a concept that is sometimes interpreted as not presenting them in any public setting.

Lying in a bed with both his hands wrapped in white bandages, one of the two North Korean POWs looked bewildered when he indicated — by nodding or shaking his head — that he didn’t know he was fighting Ukraine ​when he was captured or that he was now in Ukraine.

When he was sent to the front line on Jan. 3, he said he was only told that the North Korean troops “would train as if we were in real combat.”

“I saw my colleagues dying next to me,” he said. “I was hiding in a dugout when I got injured.”

When asked whether he wanted to return home, the soldier asked if the Ukrainians were good people. When the interpreter said yes, he said in a weak but pleading voice: “I want to live here.”

The other North Korean soldier had a bandage wrapped around his ​wounded jaw and did not speak. He nodded when he was asked whether he had parents in North Korea. But he shook his head when​ he was asked whether they knew where he was.

“​The video clip of the two soldiers shows that Kim Jong-un has not been able to find a way to justify his country’s participation in the Russia-Ukraine war to his people,” said Kang Dong-wan, an expert on North Korea at Dong-A University in South Korea. “It also showed that the North Korean troops are being wasted as cannon fodder.”

The two soldiers belonged to the Reconnaissance General Bureau, the North Korean military’s intelligence arm, the South Korean lawmakers told journalists in a briefing. The lawmakers said that when the soldiers were sent to the war, their government had promised to treat them as “heroes.”

The soldiers were captured in the Kursk region of western Russia, where North Korean forces were fighting to help Russia regain territory seized by Ukraine during a surprise cross-border incursion last summer.

​The North Korean troops were shooting at drones flying in the distance in futile attempts to destroy them, the South Korean intelligence agency told lawmakers, citing battlefield footage that it analyzed. They were also making reckless charges at their enemies without proper artillery support from the rear, it was quoted as saying.

Mr. Kim is believed to reap billions of dollars worth of oil, food and weapon technologies in return for its supply of troops and weapons to Russia, according to South Korean analysts and officials. But the troop deployment was so rushed that the ​North Korean soldiers were poorly prepared for modern warfare, especially drone attacks, they said.

On Sunday, Mr. Zelensky said that Ukraine was “ready to hand over Kim Jong-un’s soldiers to him if he can organize their exchange for our warriors who are being held captive in Russia.”

“For those North Korean soldiers who do not wish to return, there may be other options available. In particular, those who express a desire to bring peace closer by spreading the truth about this war in Korean will be given that opportunity,” he added.

Professor Kang said that by exposing the face of one North Korean soldier and his wish to remain in Ukraine, the Ukrainian authorities were endangering his safety should he be sent back to North Korea, where his statement would be seen as an act of betrayal.

​If any North Korean POWs wanted to defect to South Korea, the Seoul government was ready to negotiate with Kyiv, the South Korean lawmakers quoted the intelligence agency as saying.